Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 251655
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1255 PM EDT WED MAY 25 2016

.SYNOPSIS...
A ridge of high pressure will build over the northeastern U.S.
bringing a noticeably more summer-like pattern through at least
the first half of the upcoming holiday weekend. Cooler and showery
weather may arrive for Memorial Day.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
a veil of cirrus and cirrostratus clouds streaming in from the
west will dim the sunshine at times through this afternoon
(mainly across central and southern PA).

Summer-like temperatures are in store again today. Diurnal ranges
may be 30 to 40 degrees in some places today with highs more like
mid-July. Afternoon RH`s will dip into the 20 to 30 pct range.
Thus, it will be tough to get any cu to pop (especially with the
aforementioned cirrostratus deck trimming the insolation and sfc
temp by a tad). If they do develop, the cu will be over the
ridges and very sparse in coverage. One exception may be over the
NE as some deeper convection could make a weak/isolated shower or
two over central NY and drop it down through the Endless
Mountains late in the day. Otherwise, POPs will be near zero.

Mid to late afternoon max temps should be 1-3 degrees warmer than
Tuesday thanks to the sunshine and a slightly milder start to the
day in most places.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
Clouds start to increase from the west late tonight. But, it
should remain clear in the eastern half of the area all night. The
wind never quite dies off, so very mild mins are expected. The low
level moisture/dewpoints should be on the rise. A spot or two in
the southern tier may not go below 60F. Will keep POPs low for the
overnight, but a stray shower is possible by sunrise in the
Laurels.

Muggy is the word for Thursday. Most guidance brings dewpoints
into the 60s all over the region. The limiting factors for
convection will probably be the presence of a capping inversion
around 12kft at the top of some morning mid-level clouds. But,
the clouds may slide to the east a bit and allow the heating to
bring the W/NW into the 80s. This results in CAPE near/over
1000J/kg. All the convection should be diurnally-driven, but the
GFS does ride a very weak short-wave trough right overhead at peak
heating time, too. Thus, it is more bullish on the QPF/POPs than
the NAM and ECMWF which make very little precip. POPs will be
held at 50 pct over the Alleghenies and 20-40 pct in the rest of
the region for the afternoon and early evening. These numbers may
be too a few pct points too high, but the cap may seriously limit
deep convection.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The large scale pattern has a decidedly summertime look and feel
to it through Memorial Day weekend and into next week with light
winds aloft and a prevailing ridge across the northeast CONUS.
Temperatures will average above normal with the core of the `hot`
weather front-loaded Friday-Sunday before trending modestly toward
late May/early June climatology. Precipitation risk early in the
period should be characterized by diurnal convection with the
highest probs occurring during peak afternoon heating, augmented
at times perhaps by weak disturbances drifting through aloft. Max
POP may be centered on or around Memorial Day as weak shortwave
suppresses heights as it passes by to the north and some interaction
takes place with `tropical` system migrating toward the southeast
U.S. coast. Latest NHC forecast this area of disturbed weather has
a 50% chance of development within the next 5 days.

&&

.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
High pressure will provide the region with a warm and sunny day
with just varying amounts of high-level cirrus and cirrostratus.
VFR conditions will prevail.

500 mb heights rise a little today and the llvl pressure gradient
weakens a bit this aft...so I am not expecting the west to
southwest wind gusts to exceed 12-15 kts. Still with the high
late May sun angle...the airmass will likely still mix to about
7000 feet.

There could be a few showers and thunderstorms late Thursday.
Not totally sold on this...as the mid and upper wave potentially
triggering the convection will be weakening as it approaches, and
dewpoints are relatively low to begin with (and have to come up a
lot higher) for any appreciable convection to fire. Somewhat a
better chance for scattered afternoon shra/tsra on Friday.

OUTLOOK...

Thu-Sun...Isold...mainly pm tsra impacts possible.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Dangelo/Lambert
NEAR TERM...Dangelo/Lambert
SHORT TERM...Dangelo
LONG TERM...Steinbugl
AVIATION...Lambert/Martin


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